Finding a defining moment in the forty-year career of America’s biggest rock band is a tricky task. Should we remember them as the hungry young rock gods that recorded a string of riff-fueled classics in the seventies? The pioneers of the rock / rap fusion with Run DMC’s cover of Walk This Way? Or the ageing chart toppers playing tear jerkers like I Don’t Wanna Miss A Thing? The only thing that remains constant all the way through is Joe Perry and Brad Witford’s super tasteful and toneful guitar parts.